http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52209
Bug #: 52209
Summary: wrong code at -O0
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
[regehr@gamow 2]$ icc -Wall small.c
[regehr@gamow 2]$ ./a.out
-1
[regehr@gamow 2]$ clang -Wall small.c
[regehr@gamow 2]$ ./a.out
-1
[regehr@gamow 2]$ current-gcc -O0 small.c
[regehr@gamow 2]$ ./a.out
1
[regehr@gamow 2]$ current-gcc -O1 small.c
[regehr@gamow 2]$ ./a.out
-1
[regehr@gamow 2]$ cat small.c
int printf (const char *, ...);
struct S0
{
int f2:1;
};
static struct S0 c;
int b;
int main (void)
{
b = -1 ^ c.f2;
printf ("%d\n", b);
return 0;
}
[regehr@gamow 2]$ current-gcc -v
Using built-in specs.
COLLECT_GCC=current-gcc
COLLECT_LTO_WRAPPER=/uusoc/exports/scratch/regehr/z/compiler-install/gcc-r184082-install/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../configure --with-libelf=/usr/local --enable-lto
--prefix=/home/regehr/z/compiler-install/gcc-r184082-install
--program-prefix=r184082- --enable-languages=c,c++
Thread model: posix
gcc version 4.7.0 20120210 (experimental) (GCC)
